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Arecibo Synergy with GLAST (and other gamma-ray telescopes)

Gamma-ray Large Area Space Telescope. Arecibo Synergy with GLAST (and other gamma-ray telescopes) Frontiers of Astronomy with the World’s Largest Radio Telescope 12 September 2007 Dave Thompson GLAST Large Area Telescope Multiwavelength Coordinator David.J.Thompson@nasa.gov

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Arecibo Synergy with GLAST (and other gamma-ray telescopes)

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  1. Gamma-ray Large Area Space Telescope Arecibo Synergy with GLAST (and other gamma-ray telescopes) Frontiers of Astronomy with the World’s Largest Radio Telescope 12 September 2007 Dave Thompson GLAST Large Area Telescope Multiwavelength Coordinator David.J.Thompson@nasa.gov for the GLAST Mission Team see http://glast.gsfc.nasa.gov and links therein

  2. GLAST LAT AGILE TeV Known Gamma-ray Sources Are Multiwavelength Gamma-ray sources are nonthermal, typically produced by interactions of high-energy particles. Known classes of gamma-ray sources are multiwavelength objects, seen across much of the spectrum. INTEGRAL GLAST GBM Swift

  3. Gamma-ray Facilities: More Numerous, More Capable Swift GLAST INTEGRAL ARGO-YBJ H.E.S.S. CANGAROO Milagro MAGIC VERITAS

  4. GLAST: Gamma-ray Large Area Space Telescope Two GLAST instruments: Large Area Telescope LAT: 20 MeV – >300 GeV (LAT was originally called GLAST by itself) LAT field of view ~2.5 sr GLAST Burst Monitor GBM: 10 keV – 25 MeV GBM field of view ~9 sr Launch: This Winter Lifetime: 5 years minimum, 10 years goal

  5. What Do Gamma-ray Measurements Offer? • Huge energy range – 9+ orders of magnitude • All-sky coverage, from both ground and space (GLAST will see the entire sky every three hours) • Excellent sensitivity compared to previous instruments (GLAST LAT is about 30 times more sensitive than EGRET on the Compton Gamma Ray Observatory) • Good source locations – 1 arcmin in many cases • High time resolution for individual photons • Imaging for some extended sources

  6. Some Other Needs for Astrophysics • Distance – redshift, Dispersion Measure, proper motion, column density • Composition – spectroscopy • Precise source locations and imaging • Velocities • Polarization • Magnetic fields • Theories to connect the observations to physical models

  7. What gamma-ray science topics offer the best opportunities for cooperation with the Arecibo telescope? • Some possibilities: • Gamma-ray bursts (talk tomorrow) • Diffuse Galactic emission • Blazars • Radio galaxies • Microquasars • Pulsars (already discussed by Alice Harding) • Special thanks to Chris Salter for advice! So far, gamma-ray telescopes have only seen the brightest objects – the “tip of the iceberg.” The fainter sources are where Arecibo will be critical.

  8. Diffuse Emission How do the GALFACTS and GALPROP/gamma-ray studies compare in interpreting the Galactic magnetic field/particle distributions? What do these results imply about particle confinement and propagation? Can we use this information to search for local sources of cosmic rays? • Diffuse gamma-ray emission comes from particle interactions with matter and photon fields. Due to the limited angular resolution of gamma-ray detectors, it also represents a significant background. • The model we use (shown above) uses GALPROP, a cosmic-ray propagation code that incorporates information about gas, radiation, and magnetic fields. • The Arecibo GALFACTS program is strongly complementary to the gamma-ray diffuse study.

  9. Blazars • Blazars are a major gamma-ray source class. • There is some evidence of correlation between gamma-ray flares and emergence of new radio components of the jet, seen in VLBI. • Several VLBI programs are monitoring blazars for GLAST (MOJAVE, VIPS, Boston, Australian). • GLAST is expected to see more than 1000 blazars. Most will not be bright radio sources. • Higher sensitivity VLBI measurements will be needed. What do the combined radio/gamma-ray observations tell us about particle acceleration and interaction – processes, location? What can this information reveal about jet formation and collimation?

  10. Radio Galaxies Left: TeV and radio images of M87, one of a handful of radio galaxies seen in gamma rays. Right: TeV variability of M87. Is the gamma-ray variability related to changes in the jet? In the core? What about fainter radio galaxies?

  11. Microquasars – Binary Systems LSI 5039 – compact object in orbit around an O star. Gamma-ray emission varies during the 4 day orbit. VLBI suggests that the emission comes from a jet. LSI +61 303 – compact object in orbit around a Be star. Gamma-ray emission varies during the 26 day orbit. VLBI suggests that the emission comes from a pulsar wind. What sort of compact object? How are the particles accelerated? Are there different types of such high-mass binary systems?

  12. The Unknown Over half the sources in the third EGRET catalog remain unidentified. GLAST will detect many more sources. Identifying and understanding such sources will be a multiwavelength challenge. What other types of objects produce high-energy gamma rays and radio? Are there radio-quiet gamma-ray sources (e.g. beamed)?

  13. Summary The nonthermal nature of high-energy gamma-ray emission almost assures that gamma-ray sources will be radio sources. The new generation of gamma-ray telescopes is already expanding the number and types of sources, and this process will accelerate with GLAST. Radio, especially the great sensitivity of Arecibo, will be a critical partner with gamma-ray astrophysics.

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